DHT-treated Mice Research Articles

Regulation of Adenosine 5′,Monophosphate-Activated Protein Kinase and Lipogenesis by Androgens Contributes to Visceral Obesity in an Estrogen-Deficient State

Menopause is associated with an accumulation of visceral fat. An emerging concept suggests that relatively elevated levels of circulating androgens, compared with estrogens in postmenopausal women, underlie this shift in body fat distribution. In this study we administered dihydrotestosterone (DHT) to ovariectomized mice to examine the effect of relative androgen excess on adipose tissue distribution and function in estrogen-deficient mice. Compared with controls, DHT-treated mice exhibited increased body weight and visceral fat mass associated with triglyceride accumulation. Phosphorylation of AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase was significantly decreased by DHT in visceral fat. In 3T3-L1 cells, DHT decreased phosphorylation of AMPK in a dose-dependent manner. In addition, DHT increased the expression of lipogenic genes (fatty acid synthase, sterol regulatory element binding protein-2, and lipoprotein lipase) in visceral fat. These data provide the first in vivo evidence that an increased androgen to estrogen ratio can promote visceral fat accumulation by inhibiting AMPK activation and stimulating lipogenesis.

Sex steroids regulate pro- and anti-inflammatory cytokine release by macrophages after trauma-hemorrhage.

Studies indicate that macrophage immune responses in males are depressed after trauma-hemorrhage, whereas they are enhanced in females under such conditions. Nonetheless, the involvement of male and female sex steroids in this gender-dependent dimorphic immune response after trauma-hemorrhage remains unclear. To study this, male C3H/HeN mice were castrated and treated with pellets containing either vehicle, 5alpha-dihydrotestosterone (DHT), 17beta-estradiol, or a combination of both steroid hormones for 14 days before soft tissue trauma (i.e., laparotomy) and hemorrhagic shock (35 +/- 5 mmHg for 90 min followed by adequate fluid resuscitation) or a sham operation. Twenty-four hours later the animals were killed, plasma was obtained, and Kupffer cell and splenic and peritoneal macrophage cultures were established. For DHT-treated mice, we observed significantly decreased releases of the proinflammatory cytokines interleukin 1beta (IL-1beta) and IL-6 by splenic macrophage (-50 and -57%, respectively) and peritoneal macrophage (-51 and -52%, respectively) cultures after trauma-hemorrhage compared with releases by cultures of cells from mice subjected to a sham operation; in contrast, responses of splenic and peritoneal macrophage cultures from other groups subjected to trauma-hemorrhage did not change significantly. In addition, only DHT-treated animals exhibited increased Kupffer cell IL-6 release (+634%). The release of IL-10 in DHT-treated hemorrhaged animals was increased compared with that in sham-operated animals but was decreased in estrogen-treated mice under such conditions. These results suggest that male and female sex steroids exhibit divergent immunomodulatory properties with respect to cell-mediated immune responses after trauma-hemorrhage.

Maintenance of decidual cell reaction by androgens in the mouse.

In the mouse, estrogen and progesterone are required to prime the uterus for decidual cell reaction (DCR) in response to an intraluminal stimulus and, once DCR is induced, progesterone is required to maintain DCR. However, some evidence indicates that certain nonprogestational steroid hormones may also be involved in regulating DCR. The present study determined whether androgen plays any role in DCR. Adult CD1 mice were ovariectomized and treated with a regimen of estradiol and progesterone to prime the uterus for DCR and to maintain DCR. Sesame oil was injected into the uterine lumen to induce DCR on Day 5 of the treatment. DCR was determined by deciduomal weight-the difference between the wet weights of oil-injected and noninjected uterine horns. Testosterone, given at 1 mg/day during Days 3-5, could not replace progesterone in priming the uterus for DCR. However, the same dose of testosterone given during Days 6-8 maintained DCR. Alkaline phosphatase activity, a bio-marker for DCR, was present in the deciduoma maintained by either progesterone or testosterone, although the distribution of this enzyme activity was more intense in the antimesometrial pole in progesterone-maintained deciduoma. A nonaromatizable androgen, 5 alpha-dihydrotestosterone (DHT), was also effective in maintaining DCR, and this action of DHT was blocked by an androgen receptor antagonist, hydroxyflutamide. The relative potency of DHT in maintaining DCR was similar to that of progesterone. However, the regression of the deciduoma appeared to be advanced in DHT-treated mice. Ovariectomy on Day 6 of pregnancy resulted in resorption of the conceptus and regression of the decidua within 48 h. Treatment with DHT at the time of ovariectomy could not prevent fetal resorption, but it delayed the regression of decidua, as indicated, in part, by the presence of granulated metrial gland cells. In summary, androgen cannot prime the uterus for DCR, but it can maintain DCR once it is induced. The physiological significance of this finding remains to be determined.

Androgen dependence and tissue specificity of renin messenger RNA expression in mice

Testosterone, a steroid hormone which increases blood pressure by hitherto unknown mechanisms, is known to induce renin synthesis in the submandibular gland (SMG) of mice. Since renin as well as all other components of the renin-angiotensin system are present in organs important for cardiovascular control, e.g. the kidney, heart, adrenal gland and brain, it is of interest to study the effect of testosterone on renin gene expression in these organs. Renin messenger (m) RNA concentrations were measured by a solution hybridization assay using a 32P-labeled mouse SMG renin complementary (c) RNA as a radioactive probe (detection limit: 1 pg renin mRNA). Measurements were performed after 2 h and after 2, 7, 14 and 21 days of dihydrotestosterone (DHT) treatment in female NMRI mice. Renin mRNA concentration (values are expressed as pg renin mRNA/ micrograms total RNA) in the SMG was significantly increased after 7 days (108 +/- 22 in controls versus 630 +/- 101 in DHT-treated mice), after 14 days (83 +/- 15 in controls versus 743 +/- 83 in DHT-treated mice) and after 21 days (107 +/- 30 in controls versus 579 +/- 76 in DHT-treated mice), but did not reach levels found in untreated male NMRI mice (1021 +/- 84). In the kidney, a decrease was observed within 21 days, from 43 +/- 4 and 40 +/- 4 to 29 +/- 2 and 22 +/- 1.7 pg/micrograms in controls and DHT-treated groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of dihydrotestosterone on follicular development, ovulation and reproductive capacity of mice.

A single injection of a 5 alpha-dihydrotestosterone (DHT) was administered to cyclic female mice on the day of metoestrus. DHT (1 mg) prolonged the dioestrous stage of the cycle by 24 h and there were 50% fewer large (normal) follicles than in oil-injected controls. Degenerating ova were observed in the oviduct of 70% of the DHT-treated mice and there was a significant reduction in the numbers of females becoming pregnant and bearing normal fetuses.

Blockade by vitamin A of the occurrence of permanent vaginal changes in mice treated neonatally with 5?-dihydrotestosterone

Estrogen-independent, persistent proliferation and cornification of the vaginal epithelium occurred in ovariectomized adult mice which had received neonatal injections of 50 microgram 5alpha-dihydrotestosterone (DHT). The occurrence of the permanent vaginal changes was prevented by injections of 200 IU vitamin A acetate (VA) given simultaneously with DHT. In 45% of the DHT plus VA-treated, ovariectomized mice, clear cells with pale cytoplasm appeared in the basal layer of the degenerating epithelium, while they came out in the epithelium of 13% of the ovariectomized mice receiving neonatal injections of DHT alone. For suppressing the permanent vaginal changes, including high mitotic rate, more than 1 month was required after the combined treatment. However, the occurrence of the permanent changes was not blocked by VA given after the DHT treatment. Permanent proliferation and squamous metaplasia took place in the uterine epithelium of the DHT-treated mice. Neonatal injections of VA also prevented the occurrence of the permanent uterine changes when given simultaneously with DHT but not when given after the androgen treatment.

Effects of Progesterone plus Estradiol on Vaginal Epithelium Showing Estrogen-Independent Proliferation and Cornification in Neonatally Estrogenized and Androgenized Mice

Studies were undertaken to investigate vaginal response to progesterone plus estradiol in neonatally estrogenized or androgenized, ovariectomized adult mice showing estrogen-independent persistent alterations in the vaginal epithelium. Group 1 of C57BL/Tw strain mice were controls receiving only the oil vehicle. For 5 days from day of birth, Group 2 was given sc injections of 50 mcg of estradiol-17beta (E2) and Group 3 was given 100 mcg of 5alpha-dihydrotestosterone (DHT). All mice were ovariectomized at 10 days of age. 10 animals of each group were sacrificed at 60 days of age (Groups 1a, 2a, and 3a). 10 other animals in each group were given daily sc injections of 2 mg of progesterone plus .01 mcg of E2 for 5 consecutive days beginning at 60 days of age; they were killed on the day following the last injection (Groups 1b, 2b, and 3b). Vaginas were removed for examination. In the 60-day-old ovariectomized control group, the vagina epithelium was atrophic. In mice given E2 or DHT neonatially (Groups 2a and 2b) the epithelium was markedly proliferated. Superficial layers of the epithelium were undergoing cornification or parakeratosis in some areas in all E2-treated and in 5 of 10 DHT-treated mice. The remaining 5 androgenized mice had both mucified and cornified areas of the superficial epithelium. In mice given DHT neonatally, vaginal cornification varied with the age at ovariectomy. The presence of the ovaries for a longer period enhanced proliferation and cornification. Findings appear to indicate that, except in the fornico-cervical region, the response of epithelial cells to progesterone plus E2 was markedly affected by neonatal injections of E2 or DHT. The changes induced by neonatal injections of E2 or DHT.